Field of the Disclosure
Embodiments of the present disclosure generally relate to radar systems, and more specifically relates to distributed processing of radar signals in a radar system.
Description of the Related Art
A new class of safety systems, referred to as advanced driver assistance systems (ADAS), has been introduced into automobiles to reduce human operation error. These systems are enabled by smart sensors based primarily on millimeter-wave automotive radars. The proliferation of such assistance systems, which may provide functionality such as rear-view facing cameras, electronic stability control, and vision-based pedestrian detection systems, has been enabled in part by improvements in microcontroller and sensor technologies. Enhanced embedded radar-based solutions are enabling complementary safety features for ADAS designers.
In an automotive radar system, one or more radar sensors may be used to detect obstacles around the vehicle and the speeds of the detected objects relative to the vehicle. A processing unit in the radar system may determine the appropriate action needed, e.g., to avoid a collision or to reduce collateral damage, based on signals generated by the radar sensors. Current automotive radar systems are capable of detecting objects and obstacles around a vehicle, the position of any detected objects and obstacles relative to the vehicle, and the speed of any detected objects and obstacles relative to the vehicle. Via the processing unit, the radar system may, for example, alert the vehicle driver about potential danger, prevent a collision by controlling the vehicle in a dangerous situation, take over partial control of the vehicle, or assist the driver with parking the vehicle.
Automotive radar systems often use frequency modulated continuous wave (FMCW) technology. Such radar systems transmit chirp signals with linearly varying frequency. The reflected signal from an object (or objects) is mixed with the transmitted signal frequencies to generate a beat signal, which contains the range and Doppler information for object identification. The further away the object is from the transmitter in the vehicle, the greater the beat frequency. The higher the relative speed of the object to the vehicle, the higher the Doppler frequency. In addition, multiple transmit and receive antennas are often used to enhance the signal to noise ratio (SNR) and obtain the angle of the object relative to the vehicle.
Automotive radars are often classified into three groups—short range Radar (SRR), medium range Radar (MRR), and long range radar (LRR). In general, LRRs are designed to provide the highest range for object detection with smaller field of view (FOV) whereas SRRs provide the highest FOV with corresponding reduction in range of detected objects. The angular resolution depends on the number of antennas in the system. A typical SRR system uses 4 receive antennas and a typical LRR system uses 8 or more antennas. A typical MRR system may have either 4 or 8 antennas depending on the application of the system.
The signals received via the antennas are mixed with the transmitted signal frequencies, and the resulting beat signals (one per antenna) are filtered and converted to digital beat signals. Signal processing is then performed on the digitized beat signals to extract the range, velocity, and angle of potential objects in the view of the radar. The signal processing is typically performed in a central processing unit. The compute power and amount of memory needed to perform this centralized signal processing increases linearly with the number of antennas.